Field of the Invention
The subject matter disclosed herein relates to sensing information associated with switching devices and, more specifically, to sensing this information according to a wide range of operating conditions.
Brief Description of the Related Art
Different types of switching devices (e.g., electrical contacts, switches, and so forth) are used in various environments. For example, a power generation plant uses a large number of electrical contacts (e.g., switches and relays). The electrical contacts in a power generation plant can be used to control a wide variety of equipment such as motors, pumps, solenoids and lights. A control system needs to monitor the electrical contacts within the power plant to determine their status in order to ensure that certain functions associated with the process are being performed. In particular, the control system determines whether the electrical contacts are on or off, or whether there is a fault near the contacts such as open field wires or shorted field wires or grounded field wires that affect the ability of the contacts to perform their intended function.
One approach that a control system uses to monitor the status of the electrical contacts is to send an electrical voltage (e.g., a direct current voltage (DC) or an alternating current (AC) voltage) to the contacts in the field and determine whether this voltage can be detected. The voltage, which is provided to the electrical contacts for detection, is known as a wetting voltage. If the wetting voltage levels are high, galvanic isolation in the circuits is used as a safety measure while detecting the existence of voltage. Detecting the voltage is an indication that the electrical contact is on or off. A wetting current is associated with the wetting voltage.
Various problems have existed with previous devices. For example, the contacts need to be isolated from the control system due to the application of high wetting voltage, or damage to the control system may occur. Also, the control system may need to handle a wide variety of different voltages, but previous devices only handle voltages within a narrow range. Previous devices have also been inflexible in the sense that they cannot be easily changed or modified over time to account for changes in the operating environment. All of these problems have resulted in general dissatisfaction with previous approaches.